Air As Particles
Lecture
FOSS Kit Chemical Interactions
Investigation 3
Air in Syringe
Foam Cube Summary
Foam Cube Summary
  The density of the air particles in each foam cube is
about even before the surrounding air is
compressed.
  The cells in the closed-cell foam are all isolated
and sealed.
  Examples: Bubble Wrap and
  Blue Foam Cube
Closed Cell Cube
Foam Cube Summary
  The cells in the open-cell foam are all connected to
one another.
  The cube is a mass of channels and pathways that
connect throughout the cube.
  Air particles can pass easily through the
  connected cells.
  Example: Grey Foam Cube
Open Cell Cube
Closed Cell Cube (After Pressure)
Closed Cell Cube (After Pressure)
  The air inside the cells of the closed-cell
foam gets compressed.   The cells get smaller.   Smaller cells makes the whole cube get
smaller. Closed Cell Cube (After Pressure)
 The particles get closer together
and the cells get smaller, but each
cell has the same number of
particles inside. Open Cell Cube (After Pressure)
Open Cell Cube (After Pressure)
  The air inside the open-cell foam is
compressed when the surrounding air is
compressed.   The size of the cells doesn’t change, but
the number of particles crowded into the
cells increases. Comparing Foam Cubes
Distance Between Particles
  The distance between the air particles is
the same in the open-cell and closedcell foam before the pressure. Distance Between Particles
  Distance between the air particles is the
same in the open-cell and closed-cell
foam after pressure.  There are, however, twice as many
particles in the cells in the open-cell
cube. Gas in Syringe
  Foss Web Multimedia: Gas In Syringe
  http://www.fossweb.com/
Information on Gas (As Matter and Particles)
  Gases are composed of individual particles.
  The particles are not connected to one another.
  Move through space freely.   Travel in straight lines until they run into
something.
  Collision of gas particles (i.e. in a syringe)
bounce off and keep going in a different
direction still in a strait line.
Air as Mixture
  Air is the name of the mixture of gases that
form Earth’s atmosphere.   Composed mostly of nitrogen (N2)   Nitrogen is gas particle N2   Also in air is Oxygen (O2) particles, a few
Argon (Ar) particles, and a few Carbon
Dioxide (CO2) and water (H20) particles. Gas Particles
  Very, very small in size.
  Cubic centimeter of air (like the cubes)
contains 27 quintillion particles
  27,000,000,000,000,000,000
Air Particles
  Every air particle crashes into another air
particles (or some other object) 10 billion times
per second!
  Particles of gas are far apart.   Compare to a basketball in a room:
  Space between is 2.3 m (7.5’) apart
  Move at 300 m/s (670 mph)
What is between an air
particle?
 Nothing!
 Void.
 There is just space between
particles, no matter. Compressed Air
  Because gas particles are pretty far
apart, with only space between them,
they can be forced closer together.   Force on gas (i.e. like pushing down on
the plunger of a syringe, the air particles
can be pushed closer together.
 Compressed air!
Why can’t you push the
particles until they touch?   The fast-moving particles push back on the
syringe plunger with a force when they hit it.   As particles in gas get closer together, they
hit the plunger more frequently.   The harder you push, the harder they push.   There is a limit to how close together you can
push the air particles. What happens when force is removed from
the syringe plunger?
  When force applied to the syringe plunger is
removed:
  the particles inside the syringe push up
on the plunger and it moves out of the
syringe barrel.   It moves out until the force applied by the
air particles pushing the plunger up is
equal to the force applied by the air
particles outside pushing the plunger
down. FOSS Web Multimedia
  Periodic Table   Gas in Syringe •  http://www.fossweb.com/